The subject invention relates generally to combustors. More particularly, the subject invention relates to fuel nozzle fuel and air premixers.
Combustors typically include one or more fuel nozzles that introduce a fuel or a mixture of fuel and air to a combustion chamber where it is ignited. Mixing of fuel and air prior to combustion allows for lower flame temperatures than at a stoichiometric condition, resulting in a reduction of nitrogen oxide (NOx) emissions. Typically, fuel flows through a nozzle and fuel jets are injected into a cross flow of air flowing axially along the nozzle. Injecting fuel into the cross flow, however, produces low speed recirculation zones of fuel-air mix downstream of the fuel jets. With many fuels having high flame speeds and short blow off times, such as fuels that are high in H2 content, flameholding is likely to occur in the recirculation zones, resulting in damage to the nozzle and other combustor components. A fuel nozzle premixer that reduces flow anomalies such as recirculation would be well received in the art.